 Because it's dealing with the effectiveness of the word of God dividing even to soul and spirit. To me, it's putting together two things that are so close to each other that even that it can pierce into. I believe we are three parts, body, soul, and spirit. With the spirit, as the typical teaching, as I agree with, is God, word, and sense. And our soul, psyche, the Greek word that we have, dealing with our emotions, our will, and everything that that encompasses.